This relates generally to imaging systems, and more particularly, to imaging systems with circuit components in carrier wafers.
Modern electronic devices such as cellular telephones, cameras, and computers often use digital image sensors. Imagers (i.e., image sensors) often include a two-dimensional array of image sensing pixels. Each pixel typically includes a photosensor such as a photodiode that receives incident photons (light) and converts the photons into electrical signals. An image sensor contains an image sensor wafer containing an array of photodiodes. The image sensor wafer may be a back side illuminated (BSI) image sensor wafer that is mounted on a carrier wafer such as a silicon substrate, forming an image sensor stack. The image sensor stack is then mounted on a printed circuit substrate in an electronic device.
In conventional imaging systems, the printed circuit board on which a carrier wafer is mounted may contain circuitry (e.g., circuitry for operating the imager or other suitable circuitry). However, the amount of space on a printed circuit substrate for forming circuitry near an image sensor package may be limited. Accommodating circuit elements such as capacitors can limit the amount of space available on the printed circuit substrate for other circuitry.
It would therefore be desirable to provide improved ways of accommodating circuit elements in imaging systems.